Area Forecast Discussion
Issued by NWS Marquette, MI
Issued by NWS Marquette, MI
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740 FXUS63 KMQT 161834 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 234 PM EDT Mon Sep 16 2024 .KEY MESSAGES... - Isolated to scattered coverage of showers and non-severe thunderstorms today over western Upper MI eastward to Marquette County. - Extended stretch of well above normal temperatures continues through at least Saturday with highs mainly in the upper 70s and 80s. && .SHORT TERM /THROUGH THIS AFTERNOON/... Issued at 322 AM EDT Mon Sep 16 2024 Water vapor imagery and RAP analysis show mid-level troffing along the W Coast and a broad mid-level high encompassing the Great Lakes to New England. A shortwave moving over Hudson Bay is aiding a 25- 30kt low-level jet from northern MN ne to James Bay. This also coincides with 850mb theta-e ridging and 1000+j/kg of CAPE for parcels lifted from around 850mb. As a result, radar imagery has shown development of elevated isold shra/tsra across ne MN in the last hr or so. Closer to home, it`s an incredibly warm night for mid Sept across western to n central Upper MI in the s wind downslope areas. Temps are in the lwr 70s F as of 07z, and that`s higher than normal high temps at this time of year. Big Bay is the warm spot at 76F. Across the s central and eastern fcst area, largely decoupled winds and nothing more than sct thin ci clouds have allowed temps to fall mostly into the mid 50s to lwr 60s F range. Patchy fog has formed in that area as well. Developing shra/tsra in ne MN will likely further develop/push out across western Lake Superior and may sneak into western Upper MI this morning before low-level jet weakens. Models also indicate a subtle 850mb wind shift that will further aid the convection. For now, kept pops only in the 15-25pct range, but will be monitoring radar trends over the next several hrs to determine if any increase is needed based on how coverage of shra/tsra changes. This aftn, attention turns to sfc-based convection potential. Models show quite a range of potential MLCAPE this aftn with highest values over western to n central Upper MI, ranging from around 700j/kg at the low end to 2500j/kg from the NAM at the high end. Consensus seems to run in the 1000 to ~1500j/kg range. With instability maximizing over nw Upper MI eastward to Marquette County, which is in the same area where lake breeze is likely to develop to provide a focusing mechanism, will paint that area for aftn shra/tsra with pops in the 20-50pct range. With deep layer shear under 15kt, svr storms are not expected. The lack of shear will lead to generally short-lived convection with new development occurring along outflows of the initial cells. With precipitable water upwards of around 175pct of normal, very brief hvy rainfall will be possible. Otherwise, expect another unseasonably warm day today with highs ranging thru the 80s F with some locations reaching the upper 80s. Southerly winds will hold temps to the 70s F lakeside of Lake MI. && .LONG TERM /TONIGHT THROUGH SUNDAY/... Issued at 247 AM EDT Mon Sep 16 2024 A rex block over the eastern U.S. allows us to receive warm southerly air for most of this week, before the troughing over the western U.S. finally is able to fight its way into the Upper Great Lakes and bring some much needed rainfall to the U.P. this weekend and early next week. While the strength of the ridging from the rex block to our east will decay with time this week, the anomalously warm air could allow us to bring the high max temperature record on Tuesday and possibly the high min temperature record a few evenings late this week into early next week as cloud cover increases. We may also finally see some much needed rainfall re-enter Upper Michigan late this week into early next week. The last of the showers and thunderstorms associated with the shortwave activity early this week leave the western half of the U.P. tonight as the last of the shortwaves lifts away. As this occurs, the clear skies overnight will allow the low temperatures to sink into the mid to possibly even lower 50s across the interior areas, especially over the central. Overall, expect any rainfall we do receive over the west half to be pretty light (a tenth of an inch or less), with the east half pretty much slated to receive nothing. There may be some patchy fog that develops over the south central late tonight. Should it form, low temperatures may be warmer than what is currently predicted. Expect sunny skies from Tuesday to around Thursday as ridging over us slowly decays while a vertically-stacked low lifts from the Intermountain West into the Canadian Prairies. With warm southerly air continuing to flow into our area Tuesday, we could see a few of the high daily max temperature records broken across the area, particularly in the downslope areas near Lake Superior. While Wednesday and Thursday aren`t looking to be as warm, we can still expect high temperatures in the upper 70s to lower 80s across the area, which means some spots could flirt with tying or breaking the max high temperature record even on those days. As for fire weather concerns, it does look like we could flirt with some limited concerns on Tuesday as the min RH in the interior south central could get into the lower 30 percents. However, with winds being light, not much concern is warranted at this time. Min RHs are expected to be a little higher Wednesday and Thursday, although the continued drying of fuels may be something that still needs to be monitored. While model spread increases from this weekend into early next week, the differing suites do agree that cloud cover and possibly even rainfall look to move over us late in the extended period. As the cloud cover increases Thursday night onwards, the European ensemble highlights min temperatures being anomalously warm for this time of year. Thus, we may see some high min temperature records broken from Thursday night onwards as the cloud cover could provide extra insolation and cause low temperatures to struggle to make it down into the mid to upper 50s. As the aforementioned low over the Canadian Prairies continues to lift towards Hudson Bay Thursday night into Friday, a cold front weakening with time looks to move into our neck-of-the-woods around that same time. This cold front could bring our first rainfall back across the area since today/tonight. Additional chances for rainfall look possible this weekend into early next week as another low lifts from the Desert Southwest towards the Upper Midwest. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 158 PM EDT Mon Sep 16 2024 VFR conditions will continue to hold thru this fcst period at IWD/CMX/SAW. However, there will be isold to sct shra/tsra across western Upper MI this afternoon. CMX has the best chance of seeing showers this afternoon so have included a VCSH there, but confidence is too low to include any mention of showers in IWD and SAW. Mostly southerly winds are expected this afternoon though winds at CMX will shift e-se with lake breeze passage. Some patchy is possible tonight but this is expected to stay south of the terminals. && .MARINE... Issued at 247 AM EDT Mon Sep 16 2024 Light winds of 20 knots or less continue over Lake Superior this week as high pressure ridging over the eastern U.S. influences our weather pattern for the next several days. Nevertheless, some showers and thunderstorms are possible today and tonight as a shortwave low rides along the ridging overtop us. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...TAP AVIATION...Voss MARINE...TAP